Currently, commercial office buildings and areas outside the commercial office buildings do not have adequate protection against contaminants such as chemical, biological, nerve and nuclear agents that terrorists can obtain in the open market. For example, chlorine and bromine gases can be purchased at pool supply outlets, and cyanide pellets can be purchased as jeweler's cleaning agents. If contaminates such as these are released into a building's heating, ventilation and air conditioning (“HVAC”) system there may not be any perception of danger by potential victims within the building until it is too late. For example, in the case of cyanide, just a little bit can kill you (166 ppm—LD 50).
In the past, concerns have arisen about combustion-based pollutants in air supplied to a building's HVAC system where motor vehicles operate close to its air intakes. A building protection system for such pollutants is shown in U.S. Pat. No. 5,462,485 where, to avoid toxic levels of combustion-based pollutants, the disclosed building protection system varies an amount of outside air drawn into a building in response to a concentration of such combustion-based pollutants in a stream of outside air entering the building's air intake.
Building protection systems have been developed to respond to emergency conditions caused by the presence of smoke or similar harmful gases in buildings. For example, U.S. Pat. Nos. 4,380,187 and 5,720,659 disclose using plumbing to provide life supporting oxygen to bathrooms within a building under pressure); U.S. Pat. No. 4,960,041 discloses using vents and return air to exhaust an interior of a building; U.S. Pat. No. 5,215,499 discloses using water powered fans to pressurize individual safe spaces in a building to purge contaminates in localized areas; U.S. Pat. No. 6,293,861 discloses using pressurized air to purge a building of contaminants after they are sensed in the building; and German Patent No. 27 43 107 discloses cutting off inlet air to an HVAC system when contaminants are detected in an inlet air stream.
In addition to the issues discussed above, there are also similar concerns relating to areas surrounding the outside of commercial office buildings, government buildings, central business districts (CBD's), arenas, stadiums, business campuses, and other, general indoor and outdoor gathering places where chemical, biological, nerve or radiological agents can be released to be drawn into a building's HVAC system or affect people moving in or through such outdoor areas.
In light of the above, there is a need in the art for systems and methods that address one or more of the above-identified problems.